There are a number of different types of transducers which are capable of measuring forces and pressures. One type of force transducer includes a sensor having electrodes applied to two, flexible backing sheets which are placed face to face with the electrodes separated by a pressure sensitive resistive material. Examples of such sensors are shown in U.S. Pat. Nos. 4,734,034 and 4,856,993. These two patents show a sensor which includes row and column electrodes on the two backing sheets which are oriented so as to intersect at a plurality of locations. The pressure sensitive material between the electrodes is responsive to forces applied on opposite sides of the sensor and provides a variable resistance at each of the intersections which is representative of the forces at that intersection.
Such sensors have the capability of providing force measurements at many different locations with a spatial resolution on the order of 0.050 inches or less.
The thinness and flexibility of such a sensor allows forces to be measured without significantly disturbing the objects providing those forces. This is particularly important in certain types of instrumentation where the forces being measured may change substantially if the force sensor provides any significant interference to the movement of the objects.
The force sensors shown in the above referenced patents are capable of accurately measuring forces in situations where the forces being applied to the sensors have a small component in a direction parallel to the surface of the sensor. In situations where there are significant shear forces, the performance of the force sensors described in these patents may be degraded. Additionally, the connections with the electrodes are such that the sensor is not easily tailored to different applications requiring differently shaped sensors.
Accordingly, a sensor which would be usable in applications where shear forces are encountered and which additionally is easily modified to fit the needs of different applications would be a desirable improvement.